I wouldn't recommend using any Huawei equipment unless you're capable of replacing the firmware on the device with something made by a third party. Their products are rather well known for having undocumented and widespread security holes. And when you're dealing with a security product like a firewall, that's not a good thing.

It may not be as small as you'd like, but some 3G/4G USB NICs are supported by Tomato, so you could get a Tomato-supported router with a USB port and a USB NIC, then roll your own 3G/4G router.